The purpose of the study is to investigate the efficacy of cortical gamma oscillation on visual sensory processing and cognitive function in Alzheimer's Disease (AD) patients by combining a therapeutic sensory stimulation device capable of evoking 40-Hz gamma oscillation via non-invasive visual and auditory stimulation with pre-established markers of cortical network activity, i.e., electroencephalography (EEG) and event-related potentials (ERP), to evaluate the applicability of the 40-Hz multimodel sensory stimulation as a novel therapeutic approach for treatment of AD patients.

The central hypothesis of the study is that sustained 40Hz gamma oscillatory sensory stimulation therapy will improve cognitive function in patients with AD. The further hypothesis is that the improvement in cognitive function will result from improved connectivity and cortical network function as measured by EEG and ERP.

The hypotheses will be tested by the following:

1. - Elucidate the immediate impact of gamma oscillations on sensory processing and cognitive function by assessing cognitive function and cortical network function prior to the introduction of sensory stimulation and comparing it to post-therapeutic assessments immediately following the acute administration of therapy on visual processing.
2. - Explore the short and long-term therapeutic benefits of a sub-chronic (8 weeks) treatment by assessing cognitive function and cortical network connectivity immediately after the 8 week sensory stimulation therapy. If significant changes are observed between pre-therapy and post-therapy neurophysiologic data for an individual subject, neurophysiological testing will be repeated 4 weeks following the conclusion of therapy.
3. - Investigate the correlation between neurophysiology and cognitive function by assessing cognitive function and neurophysiological measures of cortical network activity at multiple time points to determine if therapeutic changes in one domain reflect changes related to the other domain.

Inclusion Criteria:

• Individuals ages 60 and older with established diagnosis of Alzheimer's Disease as defined by the current consensus criteria for AD (Albert et al, 2011, Jack et al, 2011; McKhann et al, 2011)
• Fluent and literate in English language
• Able to consent for themselves based upon the MacArthur Competence Assessment Tool for Clinical Research
• Patients with a pre-existing positive A(beta)-PET and/or CSF tau/A(beta) markers or willingness to undergo a Lumbar Puncture (LP) with these results

Exclusion Criteria:

• Not fluent and literate in English
• Severe dementia
• Other medical conditions/neurodegenerative disease that could significantly impair cognitive abilities
• Cardiac pacemakers or any other implants that may not be compatible with MRI
• Cognitively impaired to the point the patient is unable to consent for themselves
• Claustrophobic to the point that medication is required